Case Presentation: A 44-year female with history of hypertension and chronic lower back pain was diagnosed with streptococcal pharyngitis- which was treated with azithromycin. Following that, over the next few weeks, she developed tender, erythematous nodularities (erythema nodosum), unlike the painless subcutaneous nodules that are observed in acute rheumatic fever. This was followed by oligoarticular joint pain in her left wrist, left ankle, and right wrist. The joint pain was associated with swelling, discomfort, and decreased range of motion. It was nonmigratory and unrelieved by ibuprofen. The pain led her to present to the emergency room (ER), where she was provided relief with prednisone. Echocardiogram was negative for cardiac manifestations of rheumatic fever. Lyme serology was also negative. She was started on Prednisone 60 mg which was tapered and discontinued. About one week later, the patient again presented to the ER with right ankle pain. The ankle was noted to be swollen and erythematous. The patient was again started on prednisone 60 mg daily. Further, she was started on prophylactic treatment with IM benzathine 1.2 million units every 28 days for three years. The patient returned for follow-up about one week later, and her foot pain had completely resolved. There was residual erythema and swelling. Her prednisone dosage was slowly tapered off and later switched to tapering dose of methylprednisolone. The erythema and swelling continued to improve and after 6-8 weeks, her pain and swelling had resolved and there was only a mild degree of skin discoloration. Given her clinical improvement, the patient was kept on a maintenance dose of methylprednisolone.
Discussion: Reactive arthritis is a differential that should be considered in individuals who present with joint pain following an episode of streptococcal pharyngitis. The key differences between postinfectious reactive arthritis and rheumatic fever are as follows: (1) Patients with reactive arthritis will have persistent longer-term nonmigratory joint pain that is largely unrelieved by NSAIDs and requires steroids; (2) while rheumatic fever is usually associated with painless subcutaneous nodules, reactive arthritis may present with diffuse tender erythema nodosum; (3) although long-term antibiotic treatment has a definitive role in acute rheumatic fever, the role and duration of antibiotic prophylaxis is less clear in reactive arthritis. In our patient, we determined it may be beneficial to complete a prophylactic course of IM benzathine 1.2 million units every 28 days for three years.
Conclusions: Group A beta-hemolytic streptococcus pyogenes pharyngitis elicits host immune response by synthesizing antibodies against the streptococcal M protein [1]. While this response provides future protection from similar organisms, occasionally they may also lead to an autoimmune sequelae. Common types of sequelae associated with group A beta-hemolytic streptococcus pyogenes include poststreptococcal glomerulonephritis, Sydenham chorea, and acute rheumatic fever [2]. We report a case of another but less common autoimmune sequelae: reactive arthritis.